Adaptive immunity and protection generated by nanoparticle-based vaccination against influenza virus

摘要

Each year influenza A virus (IAV) causes significant seasonal illness. The high rate of severe seasonal illness and threat of a pandemic outbreak has renewed interest in developing novel influenza vaccines. Following primary IAV infection, the development of both neutralizing antibody and a cytotoxic specific T cell response is important in whether a robust CD8~+ T cell response is generated following vaccination. Our hypothesis is that immunizations that generate local (i.e., lung) in addition to systemic immunity will offer the greatest protection against future IAV encounters. Polyanhydride nanovaccines have been shown to be efficacious in inducing antibody and T cell responses. Therefore, we tested an IAV nanovaccine for induction of both local neutralizing antibody and cytotoxic CD8~+ T cell responses. Mice were vaccinated intranasally with 200 μg of polyanhydride nanoparticles containing 5 μg hemagglutinin (HA), 5 μg nucleoprotein (NP) and 2% CpG 1668 together with 2.5 μg of free HA and NP. At various times post-vaccination, the T cell and B cell responses in the lungs and draining lymph nodes (dLNs) were measured by flow cytometry. In addition, mice were challenged with infectious IAV, and morbidity and mortality were monitored. On day 7 post nanovaccine immunization, we observed an increased frequency and number of IAV-reactive CD4~+ and CD8~+ T cells in the lungs and dLNs of mice vs. non-vaccinated control mice (Fig. 1 and not shown). Further, B cell germinal center (GC) responses were induced in the dLNs and nasal associated lymphoid tissue (NALT) by day 12 and persisted until day 30. Finally our initial challenge experiments suggest that the IAV nanovaccine may confer protection against lethal dose infection of homologous virus (not shown). The IAV nanovaccine induced antigen-experienced IAV-specific CD4~+ and CD8~+ T cell responses in the lungs and dLNs. The IAV nanovaccine also induced a strong GC response in the dLNs and NALT indicating potent ability to induce Th cell-driven B cell responses in the airway. Overall our results suggest that the nanovaccine may invoke long-lived humoral responses as well as potentially protective T cells against influenza infection. Importantly, this new vaccination strategy may induce these long-lived B cell and T cell responses both locally and systemically. Fig 1. Intranasal nanovaccine induces strong IAV-specific CD8~+ (A) and CD4~+ (B) T cell responses in the lungs at day 7 post-vaccination (n= 1 experiment with 4-5 mice per group). Fig 2. Intranasal IAV nanovaccine induces strong GC responses in the dLNs (A) and NALT (B) at days 12-30 post-vaccination. N= 3-4 mice per time point. NALT was pooled from 3-4 mice at each time given limited cell recoveries. Flow cytometry examples are from day 18.